I didn't read this whole thread so I'll apologize in advance if someone already answered this.

A lot of astro-imagers use a dedicated monocrhrome CCD camera as opposed to a OSC or One-Shot color camera (DSLR or CCD). That would explain the monochrome image. Astro-Imaging requires a lot of post processing and monochrome image capture is preferred because its a truer image with all of the data as opposed to a OSC where there is software interpolation of the data in-camera.

If you want to capture more scientifically accurate image data, go with the monochrome. If you want to take portraits of beautiful objects, planets, nebulae -- a color camera can do an excellent job.

Color is more convenient. With the monochrome, you have to use separate RGB filters, and take three sets of images (one for each channel). Then combine them in software. Color is faster (only needs 1 set of images) which is important If the object moves in the sky. A planet may rotate in only 10 minutes. If it moves while you are still imaging, then the perspective is different. You cannot combine the images very well unless you're tracking.

My suggestion: Contact this guy (DugDog) of MyAstroImages.com via his YouTube channel and ask him how he captures his images, i.e. DSLR vs a dedicated CCD or webcam, or about that particular tutorial.

This guy in the video starts with a greyscaled stacked picture. Others I've seen worked at RGB mode. How is he getting a greyscale type of stacked photographs as mine turned out to be colour? It never looked like his in the beginning.

Mr. Bean, what hemisphere was that top photo of the Milky Way shot from?

Yeah, I noticed that also and checked Mr. Bean's profile real quick - Melbourne. I had the pleasure of visiting Perth 30+ years ago, seeing Scorpius and the heart of the Milky Way overhead is something I'll never forget, back when I was in the navy and after a long cruise through dark skies on the Indian Ocean. I know you're a night sky fan Carl.....you should treat yourself to a southern hemisphere trip sometime. Milky Way, Coal Sack, Magellanic Clouds, Omega Centauri, all just spectacular. Check out the Southern Skies Star Party at Lake Titicaca.

Correct. I'm in a small town an hour+ drive north of Melbourne (Australia). Large and Small Magellanic Clouds are the 2 objects. The Southern Cross, Pointers and Coal Sack are roughly in the middle of the frame. The sky wasn't the clearest that night, but a test for the Zeiss 15mm I had picked up that day.

The 15mm as it gives that extra wide coverage. I've used the 21mm for similar types of pics. Both are excellent in sharpness. The 15mm has a hint of coma, wide open, in the extreme corners. Aside from the sharpness of the Zeiss, the infinity hard stop makes focusing sooooo much easier in the dark

I am keen to do this myself. It is about curves and levels in Photoshop to enhance the data. My version is CS 2.

But there arise a few questions:

I downloaded deep sky stacker. stacked seven colour pictures: copies of the same photograph to give it a try.

This guy in the video starts with a greyscaled stacked picture. Others I've seen worked at RGB mode. How is he getting a greyscale type of stacked photographs as mine turned out to be colour? It never looked like his in the beginning. Here's my slightly enhanced original picture Z96A3724bMASTER by Peter Hauri, on FlickrI guess it kinda deals with RGB channels. But I have no clue how to do it, even my curves and levels don't react the same way as his.

Is it a presetting in PS which he applied without mentioning it? How can I do it in CS 2?

Thanks for any technical help.

Just another question: at what ISOs are you taking nightsky photographs for stacking purposes?

I currently take them applying 600 rule at ISO 6400 to 12800, f/8 with a 16-35 USM II lens.

Cheers and thanks in advance, Peter

What exactly is a stacked photograph? How do you take one? I didn't see that in the video...

I can't help you with the stacking thing unfortunately but I gotta ask why use f/8? I use 2.8 on my 16-35 with the focus set to infinity.. That way you can keep your ISO down to a minimum and get less noise atthe same amount of time.. using the 600 rule... If you have a 30 Sec exposure using ISO 6400 @ f/8 you can go down to ISO 800 @ f/2.8 and still have a 30 sec exposure.. You'll still get the sharpness you need..

I can't help you with the stacking thing unfortunately but I gotta ask why use f/8? I use 2.8 on my 16-35 with the focus set to infinity.. That way you can keep your ISO down to a minimum and get less noise atthe same amount of time.. using the 600 rule... If you have a 30 Sec exposure using ISO 6400 @ f/8 you can go down to ISO 800 @ f/2.8 and still have a 30 sec exposure.. You'll still get the sharpness you need..

What is the 600 rule?

Thanks,

C

A rule of thumb method to calculate the maximum exposure time, for a particular focal length, before star trails become noticeable. It's simply 600 / focal length = exposure time (in seconds).

I can't help you with the stacking thing unfortunately but I gotta ask why use f/8? I use 2.8 on my 16-35 with the focus set to infinity.. That way you can keep your ISO down to a minimum and get less noise atthe same amount of time.. using the 600 rule... If you have a 30 Sec exposure using ISO 6400 @ f/8 you can go down to ISO 800 @ f/2.8 and still have a 30 sec exposure.. You'll still get the sharpness you need..

What is the 600 rule?

Thanks,

C

A rule of thumb method to calculate the maximum exposure time, for a particular focal length, before star trails become noticeable. It's simply 600 / focal length = exposure time (in seconds).

I can't help you with the stacking thing unfortunately but I gotta ask why use f/8? I use 2.8 on my 16-35 with the focus set to infinity.. That way you can keep your ISO down to a minimum and get less noise atthe same amount of time.. using the 600 rule... If you have a 30 Sec exposure using ISO 6400 @ f/8 you can go down to ISO 800 @ f/2.8 and still have a 30 sec exposure.. You'll still get the sharpness you need..

What is the 600 rule?

Thanks,

C

A rule of thumb method to calculate the maximum exposure time, for a particular focal length, before star trails become noticeable. It's simply 600 / focal length = exposure time (in seconds).

I can't help you with the stacking thing unfortunately but I gotta ask why use f/8? I use 2.8 on my 16-35 with the focus set to infinity.. That way you can keep your ISO down to a minimum and get less noise atthe same amount of time.. using the 600 rule... If you have a 30 Sec exposure using ISO 6400 @ f/8 you can go down to ISO 800 @ f/2.8 and still have a 30 sec exposure.. You'll still get the sharpness you need..

What is the 600 rule?

Thanks,

C

A rule of thumb method to calculate the maximum exposure time, for a particular focal length, before star trails become noticeable. It's simply 600 / focal length = exposure time (in seconds).

By keeping the exposure to those times or less, the stars appear as dots, not trails.

THANK YOU!!!

Wow...talk about a VERY informative post for a noob!!!!

Thank you very much!

C

ps. Do you have any insight into what stacking photos are? Is that similar to HDR photography?

There is many programs who can help you with stacking, and you use stacking for many things, which among them are stacking panoramas, HDR or focus stacking. There are great tutorials on this if you enter these names on youtube. I use Photoshop CS 6 for this, and Photoshop 5 before that and I think it works great.

Example one Panorama picture (and you can see the result earlier in this post with my shot from Shanghai). I used a 5D II with a 16-35 II. I turned the camera to portrait mode (vertically, to get more sky) and shot eight pictures free hand. What I normally do is to make sure that the pictures overlap with about 25%. After getting them on the computer just go to photoshop - file - Automate - Photomerge and then choose the option that work best for your shot.

Example two Focus Stacking. Although a lowres version of this picture, this picture is taken with the 17mm TS and is comprised of 28 pictures in one.

Focus stacking can be especially useful in macropictures as DOF is very shallow.

Mr. Bean, what hemisphere was that top photo of the Milky Way shot from?

Yeah, I noticed that also and checked Mr. Bean's profile real quick - Melbourne. I had the pleasure of visiting Perth 30+ years ago, seeing Scorpius and the heart of the Milky Way overhead is something I'll never forget, back when I was in the navy and after a long cruise through dark skies on the Indian Ocean. I know you're a night sky fan Carl.....you should treat yourself to a southern hemisphere trip sometime. Milky Way, Coal Sack, Magellanic Clouds, Omega Centauri, all just spectacular. Check out the Southern Skies Star Party at Lake Titicaca.

Correct. I'm in a small town an hour+ drive north of Melbourne (Australia). Large and Small Magellanic Clouds are the 2 objects. The Southern Cross, Pointers and Coal Sack are roughly in the middle of the frame. The sky wasn't the clearest that night, but a test for the Zeiss 15mm I had picked up that day.

The 15mm as it gives that extra wide coverage. I've used the 21mm for similar types of pics. Both are excellent in sharpness. The 15mm has a hint of coma, wide open, in the extreme corners. Aside from the sharpness of the Zeiss, the infinity hard stop makes focusing sooooo much easier in the dark

Yes, I thought they were the Magellanic Clouds...they're beautiful!

Coma wide open in the extreme corners of a 15mm lens, is still not too shabby!

If you have an opinion, what do you think of the Tokina 16-28 f/2.8, compared with the Canon 16-35? (I know both would not compare to the Zeiss).

Mr. Bean, what hemisphere was that top photo of the Milky Way shot from?

Yeah, I noticed that also and checked Mr. Bean's profile real quick - Melbourne. I had the pleasure of visiting Perth 30+ years ago, seeing Scorpius and the heart of the Milky Way overhead is something I'll never forget, back when I was in the navy and after a long cruise through dark skies on the Indian Ocean. I know you're a night sky fan Carl.....you should treat yourself to a southern hemisphere trip sometime. Milky Way, Coal Sack, Magellanic Clouds, Omega Centauri, all just spectacular. Check out the Southern Skies Star Party at Lake Titicaca.

Correct. I'm in a small town an hour+ drive north of Melbourne (Australia). Large and Small Magellanic Clouds are the 2 objects. The Southern Cross, Pointers and Coal Sack are roughly in the middle of the frame. The sky wasn't the clearest that night, but a test for the Zeiss 15mm I had picked up that day.

The 15mm as it gives that extra wide coverage. I've used the 21mm for similar types of pics. Both are excellent in sharpness. The 15mm has a hint of coma, wide open, in the extreme corners. Aside from the sharpness of the Zeiss, the infinity hard stop makes focusing sooooo much easier in the dark

Yes, I thought they were the Magellanic Clouds...they're beautiful!

Coma wide open in the extreme corners of a 15mm lens, is still not too shabby!

If you have an opinion, what do you think of the Tokina 16-28 f/2.8, compared with the Canon 16-35? (I know both would not compare to the Zeiss).

Oops, sorry CarlTN, I meant to respond to your reply the other night.

I'll probably be burnt at the stake for saying this, but, I've never been a zoom fancier for astro work. Even some of the primes in Canon's wide angle / UWA brigade suffer around the edges from coma (the original 35mm f2 I have is one of those). Hence my search for the "perfect" UWA lens. And why I ended up with the Zeiss, happily I might add.

While I've read a great deal about "sharpness" of lenses over the past 6 months or so, the only real test was to hire a few and try them. Keeping exposures brief (less than 30 seconds) was enough to sort out the better ones, and quick